Dart Requires Chilkat v11.0.0+

RSA Sign with PKCS8 Encrypted Key

See more RSA Examples

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example assumes the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final privKey = CkPrivateKey();

  // Load the private key from an RSA PEM file:
  try {
    privKey.loadAnyFormatFile('raul_privateKey.key', 'a0123456789');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final rsa = CkRsa();

  // Import the private key into the RSA component:
  try {
    rsa.usePrivateKey(privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // This example will sign a string, and receive the signature
  // in a hex-encoded string.  Therefore, set the encoding mode
  // to "hex":
  rsa.encodingMode = 'hex';

  final strData = 'This is the string to be signed.';

  // Sign the string using the sha256 hash algorithm.
  // Other valid choices are sha1, sha384, sha512 and others.
  final String hexSig;
  try {
    hexSig = rsa.signStringENC(strData, 'sha256');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print(hexSig);

  // Now verify with the public key.
  // This example shows how to use the public key from 
  // a digital certificate (.cer file)
  final cert = CkCert();
  try {
    cert.loadFromFile('raul_publicKey.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final pubKey = CkPublicKey();
  cert.getPublicKey(pubKey);

  final rsa2 = CkRsa();
  try {
    rsa2.usePublicKey(pubKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Verify the signature against the original data:
  rsa2.encodingMode = 'hex';
  try {
    rsa2.verifyStringENC(strData, 'sha256', hexSig);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Signature verified!');

  // Verify with incorrect data:
  try {
    rsa2.verifyStringENC('something else', 'sha256', hexSig);
    print('Hmmm... that\'s not right...');
  } on ChilkatException {
    print('Signature not verified! (which was expected in this case)');
  }
}